| Objective:To investigate the impairment of mental rotation in the patients with early Parkinson's disease (PD)Methods:Twenty-nine PD patients and 29 healthy subjects, matched for age, sex and education, were recruited in the study. None of the 58 subjects was demented (score≥26 on MoCA) or anxiety (score≤14 on HAMA) or depressed (score<16 on HAMD-17). The average duration of the disease was (4.3±3.5) years. The mean motor function score, assessed under levodopa therapy with the UPDRSⅡandⅢ, was (13.2±4.5) and (24.1±8.4), respectively. The Hoehn-Yahr stage had also been judged. The dosage of levodopa was calculated by levoduopa equivalent dosage (LED) with a mean dosage of (466.4±410.5) mg/d.All of the subjects were taken mental rotation test. The test was programmed using the software running on a PC. There were three different experiments which consisted of 48 realistic photos of a car, hand or foot. The subjects were asked to make the laterality judgement of the photos as correctly and as quickly as possible and to answer it by knocking two buttons. The computer would record the accuracy one by one.Data were analyzed by SPSS 17.0. The t-test and chi-square test were used to test the continuous variable and the categorical variebles respectively. The scores of MoCA, HAMA and HAMD were compared between two groups using t-test. The accuracy were analyzed in GLM-Repeated Measures with a between-subjects factor of "Group" (PD group, NC group) and two within-subjects variables of "Stimulus type"(car, hand, foot) and "Stimulus orientation" (0°,60°,120°,180°,240°,300°). Post hoc comparisons were carried out by means of ANOVA or t-test. The LSD-t test for multiple comparisons was applied when necessary. The Spearman correlation coefficient was used for assessing the possible relationship between performance in laterality judgements of car, hand or foot and the sex, age, educational level, MoCA, HAMA, HAMD, the duration of the disease, Hoehn-Yahr stage,UPDRSⅡ/Ⅲ, LED in PD patients.Results:There was significant difference of accuracy in mental rotation tests between the two groups (F (1,56)=7.727, t=0.007), the accuracy was much lower in PD group (85.0%±1.4%) than in the control group (90.6%±1.4%). There was no significant difference(t=0.803, p=0.426) of the mental rotation test of car between the PD group (89.7%±9.3%) and the control group (91.5%±7.2%). The accuracy of the mental rotation test of hand was significant lower (t=3.681, p=0.001) in the PD patients (82.5%±11.5%) than in the normal controls (91.5%±6.6%). Although there was no significant diffenrence of accuracy in the mental rotation test of foot between PD patients (82.8%±13.5%) and normal controls (88.9%±9.8%), it had a tendency to be significant. (t=1.978, p=0.053)The performance of mental rotation was correlated to the MoCA in both PD patients and normal controls.Conclusion:The present study showed that, in the early PD patients, the ability of mental rotation was impaired. A single dissociation was found between the body and non-corporeal object mental rotation in PD. Individuals with PD had an impaired ability to mentally rotate body parts but not objects. The patients with right-side onset (RPD) would commit more errors rotating body parts than patients with left-side onset (LPD). And there was a correlation between the MoCA and the performance of mental rotation in both PD patients and normal controls. |
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